The tiniest car sold in the USA posted some of the best crash-test results, the Insurance Institute for Highway Safety will announce Wednesday.

The Smart ForTwo, the twin-seat micro that's so small that two can fit in a single parking space, earned the top rating in front- and side-impact crash tests. It was rated "acceptable" for whiplash protection in rear-end crashes, the agency says.

There's an important caveat: While the frontal tests do a good job of replicating a crash against a fixed object, there is no overcoming the laws of physics when it comes to crashes against larger, heavier vehicles such as SUVs and big pickups.

"All things being equal, bigger and heavier is always better," says institute President Adrian Lund. "But among the smallest cars, the engineers of the Smart did their homework and designed a high level of safety into a very small package."

The institute's test follows government findings that gave the Smart four out of five stars on front-end crash testing on the driver's side. While the car's small-is-cool image and 36-mpg gas thriftiness made the timing of its entry in the U.S. market fortunate, safety has remained the question mark.

The new crash results are "really exciting," says Smart USA President Dave Schembri. "It really validates that small can be safe."

About 7,000 Smart cars are plying American roads since the French-made car went on sale earlier this year at list prices ranging from $11,590 to $16,590. Smart USA is part of Detroit's Penske Automotive Group (PAG), which struck a deal to import the little cars that are already sold throughout the world under a deal with Smart's parent, Germany's Daimler.

Though not quite 9 feet long, the Smart's safety secret is a high-strength cell around the driver and passenger. Because it lacks front-end crush space, Smart relies more on the car's seat belts and air bags to protect occupants.

Schembri says the Smart car is basically sold out through the end of the year with 30,000 reservations. Most are sold over the Internet, and 81% of those consumers who made a down payment for the car are going ahead with the purchase. He says a couple of owners have sent him photos of Smart cars damaged in collisions to show that they held up.

One Smart owner says the latest tests validate the faith he already had in his car.

Donald LaFavor, 76, a retired Toyota executive from Los Angeles, says he's never had the "slightest" doubt about his black ForTwo. He says his wife went along with the purchase as "an emotional supporter and thought I was crazy." But after he had to make some emergency turns on rain-slick streets earlier this year, "My wife said at that point, 'It's great.' "

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